Rapid reversed-phase high performance liquid chromatographic method for the quantification of L-Dopa (L-3,4-dihydroxyphenylalanine), non-methylated and methylated tetrahydroisoquinoline compounds from Mucuna beans

A high-performance liquid chromatographic (HPLC) assay for the extraction and quantitative determination of L-Dopa, L-3-carboxy-6,7-dihydroxy- 1,2,3,4-tetrahydroisoquinoline and 1-methyl-3-carboxy-6,7-dihydroxy- 1,2,3,4-tetrahydroisoquinoline in Mucuna pruriens var. utilis seeds has been developed. All the three compounds, L-Dopa, CDTHIQ and MCDTHIQ in the white variety of whole (4.96 g 100 g(-1), 130.3 and 116.8 mg 100 g(-1)) and dehulled (5.21 g 100 g(-1), 138.3 and 125.9 mg 100 g(-1)) seeds have been found to be significantly (P < 0.05) higher than the black variety, respectively. The method makes use of a reversed-phase system with a GIB-bonded column and yields quantitative recovery of all the three compounds, L-Dopa (101.8%), CDTHIQ (98.2%) and MCDTHIQ (94.5%). This procedure is superior to other analytical techniques currently available because of its simplicity with regard to sample preparation, the sensitivity and rapidity of the method. (C) 2001 Elsevier Science Ltd. All rights reserved.